Method for exchanging heat in vapor compression heat transfer systems and vapor compression heat transfer systems comprising intermediate heat exchangers with dual-row evaporators or condensers

ABSTRACT

A multi-step method is disclosed for exchanging heat in a vapor compression heat transfer system having a working fluid circulating therethrough. The method includes the step of circulating a working fluid comprising a fluoroolefin to an inlet of a first tube of an internal heat exchanger, through the internal heat exchanger and to an outlet thereof. Also disclosed are vapor compression heat transfer systems for exchanging heat. The systems include an evaporator, a compressor, a dual-row condenser and an intermediate heat exchanger having a first tube and a second tube. A disclosed system involves a dual-row condenser connected to the first and second intermediate heat exchanger tubes. Another disclosed system involves a dual-row evaporator connected to the first and second intermediate heat exchanger tubes.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of and claims the priority benefit of pending U.S. patent application Ser. No. 13/207,557, filed Aug. 11, 2011, which is a continuation-in-part of and claims the priority benefit of U.S. patent application Ser. No. 12/119,023, filed May 12, 2008, which claims the priority benefit of U.S. Provisional Application No. 60/928,826, filed May 11, 2007, U.S. Provisional Application No. 60/988,562, filed Nov. 16, 2007 and PCT Application No. PCT/US2007/025675, filed Dec. 17, 2007.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present disclosure relates to a method for exchanging heat in a vapor compression heat transfer system. In particular, it relates to use of an intermediate heat exchanger to improve performance of a vapor compression heat transfer system utilizing a working fluid comprising at least one fluoroolefin.

2. Description of Related Art

Methods for improving the performance of heat transfer systems, such as refrigeration systems and air conditioners, are always being sought, in order to reduce cost of operation of such systems.

When new working fluids for heat transfer systems, including vapor compression heat transfer systems, are being proposed it is important to be able to provide means of improving cooling capacity and energy efficiency for the new working fluids.

SUMMARY OF THE INVENTION

Applicants have found that the use of an internal heat exchanger in a vapor compression heat transfer system that uses a fluoroolefin provides unexpected benefits due to sub-cooling of the working fluid exiting out of the condenser. By “subcooling” is meant the reduction of the temperature of a liquid below that liquid's saturation point for a given pressure. The saturation point is the temperature at which the vapor usually would condense to a liquid, but subcooling produces a lower temperature vapor at the given pressure. By cooling a vapor below the saturation point, the net refrigeration capacity can be increased. Sub-cooling thereby improves cooling capacity and energy efficiency of a system, such as vapor compression heat transfer systems, which comprise fluoroolefins.

In particular, when the fluoroolefin 2,3,3,3-tetrafluoropropene (HFC-1234yf) is used as the working fluid, surprising results have been achieved with respect to coefficient of performance and capacity of the working fluid, as compared to the use of known working fluids such as 1,1,1,2-tetrafluoroethane (HFC-124a).

Therefore, in accordance with the present invention, the present disclosure provides a method of exchanging heat in a vapor compression heat transfer system, comprising:

-   -   (a) circulating a working fluid comprising a fluoroolefin to an         inlet of a first tube of an internal heat exchanger, through the         internal heat exchanger and to an outlet thereof;     -   (b) circulating the working fluid from the outlet of the first         tube of the internal heat exchanger to an inlet of an         evaporator, through the evaporator to evaporate the working         fluid into a gas, and through an outlet of the evaporator;     -   (c) circulating the working fluid from the outlet of the         evaporator to an inlet of a second tube of the internal heat         exchanger to transfer heat from the liquid working fluid from         the condenser to the gaseous working fluid from the evaporator,         through the internal heat exchanger, and to an outlet of the         second tube;     -   (d) circulating the working fluid from the outlet of the second         tube of the internal heat exchanger to an inlet of a compressor,         through the compressor to compress the working fluid gas, and to         an outlet of the compressor;     -   (e) circulating the working fluid from the outlet of the         compressor to an inlet of a condenser and through the condenser         to condense the compressed working fluid gas into a liquid, and         to an outlet of the condenser;     -   (f) circulating the working fluid from the outlet of the         condenser to an inlet of the first tube of the intermediate heat         exchanger to transfer heat from the liquid from the condenser to         the gas from the evaporator, and to an outlet of the second         tube; and     -   (g) circulating the working fluid from the outlet of the second         tube of the internal heat exchanger back to the evaporator.

The fluorolefin is a compound selected from the group consisting of:

-   -   (i) fluoroolefins of the formula E- or Z—R¹CH═CHR², wherein R¹         and R² are, independently, C₁ to C₆ perfluoroalkyl groups;     -   (ii) cyclic fluoroolefins of the formula         cyclo-[CX═CY(CZW)_(n)—], wherein X, Y, Z, and W, independently,         are H or F, and n is an integer from 2 to 5; and     -   (iii) fluoroolefins selected from the group consisting of:         1,2,3,3,3-pentafluoro-1-propene (CHF═CFCF₃),         1,1,3,3,3-pentafluoro-1-propene (CF₂═CHCF₃),         1,1,2,3,3-pentafluoro-1-propene (CF₂═CFCHF₂),         1,2,3,3-tetrafluoro-1-propene (CHF═CFCHF₂),         2,3,3,3-tetrafluoro-1-propene (CH₂═CFCF₃),         1,3,3,3-tetrafluoro-1-propene (CHF═CHCF₃),         1,1,2,3-tetrafluoro-1-propene (CF₂═CFCH₂F),         1,1,3,3-tetrafluoro-1-propene (CF₂═CHCHF₂),         1,2,3,3-tetrafluoro-1-propene (CHF═CFCHF₂),         3,3,3-trifluoro-1-propene (CH₂═CHCF₃), 2,3,3-trifluoro-1-propene         (CHF₂CF═CH₂); 1,1,2-trifluoro-1-propene (CH₃CF═CF₂);         1,2,3-trifluoro-1-propene (CH₂FCF═CF₂);         1,1,3-trifluoro-1-propene (CH₂FCH═CF₂);         1,3,3-trifluoro-1-propene (CHF₂CH═CHF);         1,1,1,2,3,4,4,4-octafluoro-2-butene (CF₃CF═CFCF₃);         1,1,2,3,3,4,4,4-octafluoro-1-butene (CF₃CF₂CF═CF₂);         1,1,1,2,4,4,4-heptafluoro-2-butene (CF₃CF═CHCF₃);         1,2,3,3,4,4,4-heptafluoro-1-butene (CHF═CFCF₂CF₃);         1,1,1,2,3,4,4-heptafluoro-2-butene (CHF₂CF═CFCF₃);         1,3,3,3-tetrafluoro-2-(trifluoromethyl)-1-propene ((CF₃)₂C═CHF);         1,1,3,3,4,4,4-heptafluoro-1-butene (CF₂═CHCF₂CF₃);         1,1,2,3,4,4,4-heptafluoro-1-butene (CF₂═CFCHFCF₃);         1,1,2,3,3,4,4-heptafluoro-1-butene (CF₂═CFCF₂CHF₂);         2,3,3,4,4,4-hexafluoro-1-butene (CF₃CF₂CF═CH₂);         1,3,3,4,4,4-hexafluoro-1-butene (CHF═CHCF₂CF₃);         1,2,3,4,4,4-hexafluoro-1-butene (CHF═CFCHFCF₃);         1,2,3,3,4,4-hexafluoro-1-butene (CHF═CFCF₂CHF₂);         1,1,2,3,4,4-hexafluoro-2-butene (CHF₂CF═CFCHF₂);         1,1,1,2,3,4-hexafluoro-2-butene (CH₂FCF═CFCF₃);         1,1,1,2,4,4-hexafluoro-2-butene (CHF₂CH═CFCF₃);         1,1,1,3,4,4-hexafluoro-2-butene (CF₃CH═CFCHF₂);         1,1,2,3,3,4-hexafluoro-1-butene (CF₂═CFCF₂CH₂F);         1,1,2,3,4,4-hexafluoro-1-butene (CF₂═CFCHFCHF₂);         3,3,3-trifluoro-2-(trifluoromethyl)-1-propene (CH₂═C(CF₃)₂);         1,1,1,2,4-pentafluoro-2-butene (CH₂FCH═CFCF₃);         1,1,1,3,4-pentafluoro-2-butene (CF₃CH═CFCH₂F);         3,3,4,4,4-pentafluoro-1-butene (CF₃CF₂CH═CH₂);         1,1,1,4,4-pentafluoro-2-butene (CHF₂CH═CHCF₃);         1,1,1,2,3-pentafluoro-2-butene (CH₃CF═CFCF₃);         2,3,3,4,4-pentafluoro-1-butene (CH₂═CFCF₂CHF₂);         1,1,2,4,4-pentafluoro-2-butene (CHF₂CF═CHCHF₂);         1,1,2,3,3-pentafluoro-1-butene (CH₃CF₂CF═CF₂);         1,1,2,3,4-pentafluoro-2-butene (CH₂FCF═CFCHF₂);         1,1,3,3,3-pentafluoro-2-methyl-1-propene (CF₂═C(CF₃)(CH₃));         2-(difluoromethyl)-3,3,3-trifluoro-1-propene (CH₂═C(CHF₂)(CF₃));         2,3,4,4,4-pentafluoro-1-butene (CH₂═CFCHFCF₃);         1,2,4,4,4-pentafluoro-1-butene (CHF═CFCH₂CF₃);         1,3,4,4,4-pentafluoro-1-butene (CHF═CHCHFCF₃);         1,3,3,4,4-pentafluoro-1-butene (CHF═CHCF₂CHF₂);         1,2,3,4,4-pentafluoro-1-butene (CHF═CFCHFCHF₂);         3,3,4,4-tetrafluoro-1-butene (CH₂═CHCF₂CHF₂);         1,1-difluoro-2-(difluoromethyl)-1-propene (CF₂═C(CHF₂)(CH₃));         1,3,3,3-tetrafluoro-2-methyl-1-propene (CHF═C(CF₃)(CH₃));         3,3-difluoro-2-(difluoromethyl)-1-propene (CH₂═C(CHF₂)₂);         1,1,1,2-tetrafluoro-2-butene (CF₃CF═CHCH₃);         1,1,1,3-tetrafluoro-2-butene (CH₃CF═CHCF₃);         1,1,1,2,3,4,4,5,5,5-decafluoro-2-pentene (CF₃CF═CFCF₂CF₃);         1,1,2,3,3,4,4,5,5,5-decafluoro-1-pentene (CF₂═CFCF₂CF₂CF₃);         1,1,1,4,4,4-hexafluoro-2-(trifluoromethyl)-2-butene         ((CF₃)₂C═CHCF₃); 1,1,1,2,4,4,5,5,5-nonafluoro-2-pentene         (CF₃CF═CHCF₂CF₃); 1,1,1,3,4,4,5,5,5-nonafluoro-2-pentene         (CF₃CH═CFCF₂CF₃); 1,2,3,3,4,4,5,5,5-nonafluoro-1-pentene         (CHF═CFCF₂CF₂CF₃); 1,1,3,3,4,4,5,5,5-nonafluoro-1-pentene         (CF₂═CHCF₂CF₂CF₃); 1,1,2,3,3,4,4,5,5-nonafluoro-1-pentene         (CF₂═CFCF₂CF₂CHF₂); 1,1,2,3,4,4,5,5,5-nonafluoro-2-pentene         (CHF₂CF═CFCF₂CF₃); 1,1,1,2,3,4,4,5,5-nonafluoro-2-pentene         (CF₃CF═CFCF₂CHF₂); 1,1,1,2,3,4,5,5,5-nonafluoro-2-pentene         (CF₃CF═CFCHFCF₃);         1,2,3,4,4,4-hexafluoro-3-(trifluoromethyl)-1-butene         (CHF═CFCF(CF₃)₂);         1,1,2,4,4,4-hexafluoro-3-(trifluoromethyl)-1-butene         (CF₂═CFCH(CF₃)₂);         1,1,1,4,4,4-hexafluoro-2-(trifluoromethyl)-2-butene         (CF₃CH═C(CF₃)₂);         1,1,3,4,4,4-hexafluoro-3-(trifluoromethyl)-1-butene         (CF₂═CHCF(CF₃)₂); 2,3,3,4,4,5,5,5-octafluoro-1-pentene         (CH₂═CFCF₂CF₂CF₃); 1,2,3,3,4,4,5,5-octafluoro-1-pentene         (CHF═CFCF₂CF₂CHF₂);         3,3,4,4,4-pentafluoro-2-(trifluoromethyl)-1-butene         (CH₂═C(CF₃)CF₂CF₃);         1,1,4,4,4-pentafluoro-3-(trifluoromethyl)-1-butene         (CF₂═CHCH(CF₃)₂);         1,3,4,4,4-pentafluoro-3-(trifluoromethyl)-1-butene         (CHF═CHCF(CF₃)₂);         1,1,4,4,4-pentafluoro-2-(trifluoromethyl)-1-butene         (CF₂═C(CF₃)CH₂CF₃);         3,4,4,4-tetrafluoro-3-(trifluoromethyl)-1-butene         ((CF₃)₂CFCH═CH₂); 3,3,4,4,5,5,5-heptafluoro-1-pentene         (CF₃CF₂CF₂CH═CH₂); 2,3,3,4,4,5,5-heptafluoro-1-pentene         (CH₂═CFCF₂CF₂CHF₂); 1,1,3,3,5,5,5-heptafluoro-1-butene         (CF₂═CHCF₂CH₂CF₃); 1,1,1,2,4,4,4-heptafluoro-3-methyl-2-butene         (CF₃CF═C(CF₃)(CH₃));         2,4,4,4-tetrafluoro-3-(trifluoromethyl)-1-butene         (CH₂═CFCH(CF₃)₂);         1,4,4,4-tetrafluoro-3-(trifluoromethyl)-1-butene         (CHF═CHCH(CF₃)₂);         1,1,1,4-tetrafluoro-2-(trifluoromethyl)-2-butene         (CH₂FCH═C(CF₃)₂);         1,1,1,3-tetrafluoro-2-(trifluoromethyl)-2-butene         (CH₃CF═C(CF₃)₂); 1,1,1-trifluoro-2-(trifluoromethyl)-2-butene         ((CF₃)₂C═CHCH₃); 3,4,4,5,5,5-hexafluoro-2-pentene         (CF₃CF₂CF═CHCH₃); 1,1,1,4,4,4-hexafluoro-2-methyl-2-butene         (CF₃C(CH₃)═CHCF₃); 3,3,4,5,5,5-hexafluoro-1-pentene         (CH₂═CHCF₂CHFCF₃); 4,4,4-trifluoro-2-(trifluoromethyl)-1-butene         (CH₂═C(CF₃)CH₂CF₃);         1,1,2,3,3,4,4,5,5,6,6,6-dodecafluoro-1-hexene (CF₃(CF₂)₃CF═CF₂);         1,1,1,2,2,3,4,5,5,6,6,6-dodecafluoro-3-hexene         (CF₃CF₂CF═CFCF₂CF₃);         1,1,1,4,4,4-hexafluoro-2,3-bis(trifluoromethyl)-2-butene         ((CF₃)₂C═C(CF₃)₂);         1,1,1,2,3,4,5,5,5-nonafluoro-4-(trifluoromethyl)-2-pentene         ((CF₃)₂CFCF═CFCF₃);         1,1,1,4,4,5,5,5-octafluoro-2-(trifluoromethyl)-2-pentene         ((CF₃)₂C═CHC₂F₅);         1,1,1,3,4,5,5,5-octafluoro-4-(trifluoromethyl)-2-pentene         ((CF₃)₂FCCF═CHCF₃); 3,3,4,4,5,5,6,6,6-nonafluoro-1-hexene         (CF₃CF₂CF₂CF₂CH═CH₂);         4,4,4-trifluoro-3,3-bis(trifluoromethyl)-1-butene         (CH₂═CHC(CF₃)₃);         1,1,1,4,4,4-hexafluoro-3-methyl-2-(trifluoromethyl)-2-butene         ((CF₃)₂C═C(CH₃)(CF₃));         2,3,3,5,5,5-hexafluoro-4-(trifluoromethyl)-1-pentene         (CH₂═CFCF₂CH(CF₃)₂);         1,1,1,2,4,4,5,5,5-nonafluoro-3-methyl-2-pentene         (CF₃CF═C(CH₃)CF₂CF₃);         1,1,1,5,5,5-hexafluoro-4-(trifluoromethyl)-2-pentene         (CF₃CH═CHCH(CF₃)₂); 3,4,4,5,5,6,6,6-octafluoro-2-hexene         (CF₃CF₂CF₂CF═CHCH₃); 3,3,4,4,5,5,6,6-octafluoro1-hexene         (CH₂═CHCF₂CF₂CF₂CHF₂);         1,1,1,4,4-pentafluoro-2-(trifluoromethyl)-2-pentene         ((CF₃)₂C═CHCF₂CH₃);         4,4,5,5,5-pentafluoro-2-(trifluoromethyl)-1-pentene         (CH₂═C(CF₃)CH₂C₂F₅);         3,3,4,4,5,5,5-heptafluoro-2-methyl-1-pentene         (CF₃CF₂CF₂C(CH₃)═CH₂); 4,4,5,5,6,6,6-heptafluoro-2-hexene         (CF₃CF₂CF₂CH═CHCH₃); 4,4,5,5,6,6,6-heptafluoro-1-hexene         (CH₂═CHCH₂CF₂C₂F₅); 1,1,1,2,2,3,4-heptafluoro-3-hexene         (CF₃CF₂CF═CFC₂H₅);         4,5,5,5-tetrafluoro-4-(trifluoromethyl)-1-pentene         (CH₂═CHCH₂CF(CF₃)₂);         1,1,1,2,5,5,5-heptafluoro-4-methyl-2-pentene         (CF₃CF═CHCH(CF₃)(CH₃));         1,1,1,3-tetrafluoro-2-(trifluoromethyl)-2-pentene         ((CF₃)₂C═CFC₂H₅);         1,1,1,2,3,4,4,5,5,6,6,7,7,7-tetradecafluoro-2-heptene         (CF₃CF═CCF₂CF₂C₂F₅);         1,1,1,2,2,3,4,5,5,6,6,7,7,7-tetradecafluoro-3-heptene         (CF₃CF₂CF═CFCF₂C₂F₅);         1,1,1,3,4,4,5,5,6,6,7,7,7-tridecafluoro-2-heptene         (CF₃CH═CFCF₂CF₂C₂F₅);         1,1,1,2,4,4,5,5,6,6,7,7,7-tridecafluoro-2-heptene         (CF₃CF═CHCF₂CF₂C₂F₅);         1,1,1,2,2,4,5,5,6,6,7,7,7-tridecafluoro-3-heptene         (CF₃CF₂CH═CFCF₂C₂F₅);         1,1,1,2,2,3,5,5,6,6,7,7,7-tridecafluoro-3-heptene         (CF₃CF₂CF═CHCF₂C₂F₅); pentafluoroethyl trifluorovinyl ether         (CF₂═CFOCF₂CF₃); and trifluoromethyl trifluorovinyl ether         (CF₂═CFOCF₃).

In addition, sub-cooling has been found to enhance the performance and efficiency of systems which use cross-current/counter-current heat exchange, such as those which employ either a dual-row condenser or a dual-row evaporator.

Therefore, further in accordance with the method of the present invention, the present disclosure also provides that the condensing step may comprise:

-   -   (i) circulating the working fluid to a back row of the dual-row         condenser, where the back row receives the working fluid at a         first temperature; and     -   (ii) circulating the working fluid to a front row of the         dual-row condenser, where the front row receives the working         fluid at a second temperature, where the second temperature is         less than the first temperature, so that air which travels         across the front row and the back row is preheated, whereby the         temperature of the air is greater when it reaches the back row         than when it reaches the front row.

Further in accordance with the method of the present invention, the present disclosure also provides that the evaporating step may comprise:

-   -   (i) passing the working fluid through an inlet of a dual-row         evaporator having a first row and a second row,     -   (ii) circulating the working fluid in a first row in a direction         perpendicular to the flow of fluid through the inlet of the         evaporator, and     -   (iii) circulating the working fluid in a second row in a         direction generally counter to the direction of the flow of the         working fluid through the inlet.

Also in accordance with the present invention, there is provided a vapor compression heat transfer system for exchanging heat comprising an intermediate heat exchanger in combination with a dual-row condenser or a dual-row evaporator, or both.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention may be better understood with reference to the following figures, wherein:

FIG. 1 is a schematic diagram of one embodiment of a vapor compression heat transfer system including an intermediate heat exchanger, used to practice the method of circulating a working fluid comprising a fluoroolefin through this system according to the present invention.

FIG. 1A is a cross-sectional view of one embodiment of an intermediate heat exchanger.

FIG. 2 is a perspective view of a dual-row condenser which can be used with the vapor compression heat transfer system of FIG. 1.

FIG. 3 is a perspective view of a dual-row evaporator used which can be used with the vapor compression heat transfer system of FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

One embodiment of the present disclosure provides a method of circulating a working fluid comprising a fluoroolefin through a vapor compression heat transfer system. A vapor-compression heat transfer system is a closed loop system which re-uses working fluid in multiple steps producing a cooling effect in one step and a heating effect in a different step. Such a system generally includes an evaporator, a compressor, a condenser and an expansion device, and is known in the art. Reference will be made to FIG. 1 in describing this method.

With reference to FIG. 1, liquid working fluid from a condenser 41 flows through a line to an intermediate heat exchanger, or simply IHX. The intermediate heat exchanger includes a first tube 30, which contains a relatively hot liquid working fluid, and a second tube 50, which contains a relatively colder gaseous working fluid. The first tube of the IHX is connected to the outlet line of the condenser. The liquid working fluid then flows through an expansion device 52 and through a line 62 to an evaporator 42, which is located in the vicinity of a body to cooled. In the evaporator, the working fluid is evaporated, and the vaporization of the working fluid provides cooling. The expansion device 52 may be an expansion valve, a capillary tube, an orifice tube or any other device where the working fluid may undergo an abrupt reduction in pressure. The evaporator has an outlet, through which the cold gaseous working fluid flows to the second tube 50 of the IHX, wherein the cold gaseous working fluid comes in thermal contact with the hot liquid working fluid in the first tube 30 of the IHX, and thus the cold gaseous working fluid is warmed somewhat. The gaseous working fluid flows from the second tube of the IHX through a line 63 to the inlet of a compressor 12. The gas is compressed in the compressor, and the compressed gaseous working fluid is discharged from the compressor and flows to the condenser 41 through a line 61 wherein the working fluid is condensed, thus giving off heat, and the cycle then repeats.

In an intermediate heat exchanger, the first tube containing the relatively hotter liquid working fluid and the second tube containing the relatively colder gaseous working fluid are in thermal contact, thus allowing transfer of heat from the hot liquid to the cold gas. The means by which the two tubes are in thermal contact may vary. In one embodiment, the first tube has a larger diameter than the second tube, and the second tube is disposed concentrically in the first tube, and a hot liquid in the first tube surrounds a cold gas in the second tube. This embodiment is shown in FIG. 1A, where the first tube (30 a) surrounds the second tube (50 a).

Also, in one embodiment, the working fluid in the second tube of the internal heat exchanger may flow in a countercurrent direction to the direction of flow of the working fluid in the first tube, thereby cooling the working fluid in the first tube and heating the working fluid in the second tube.

Cross-current/counter-current heat exchange may be provided in the system of FIG. 1 by a dual-row condenser or a dual-row evaporator, although it should be noted that this system is not limited to such a dual-row condensers or evaporators. Such condensers and evaporators are described in detail in U.S. Provisional Patent Application No. 60/875,982, filed Dec. 19, 2006 (now International Application PCT/US07/25675, filed Dec. 17, 2007), and may be designed particularly for working fluids that comprise non-azeotropic or near-azeotropic compositions.

Therefore, in accordance with the present invention, there is provided a vapor compression heat transfer system which comprises either a dual-row condenser, or a dual-row evaporator, or both. Such a system is the same as that described above with respect to FIG. 1, except for the description of the dual-row condenser or the dual-row evaporator.

Reference will be made to FIG. 2 to describe such a system which includes a dual-row condenser. A dual-row condenser is shown at 41 in FIG. 2. In this dual-row cross-current/counter-current design, a hot working fluid enters the condenser through a first, or back row 14, passes through the first row, and exits the condenser through a second, or front row 13. The working fluid enters first row 14 via a collector 6 inside a first pass 2 of the first row. In the first, or back row, the working fluid is cooled in a counter current manner by air, which has been heated by the second, or front row 13 of this dual-row condenser. The working fluid goes from first pass 2 of the first row 14, to a pass 3 of the second, or front row 13 by a connection 7. The working fluid then flows from pass 3 to a pass 4 in second row 13 through a connection 8, and then flows from pass 4 to a pass 5 through a connection 9. Then the sub-cooled working fluid exits the condenser by a connection 10. Air is circulated in a counter-current manner relative to the working fluid flow, as indicated by the arrow having points 11 and 12 of FIG. 2. The design shown in FIG. 2 is generic and can be used for any air-to-refrigerant condenser in stationary applications as well as in mobile applications.

Reference will be made to FIG. 3 in describing a vapor compression heat transfer system comprising a dual-row evaporator. A dual-row evaporator is shown at 42 in FIG. 3. In this dual-row cross-current/counter-current design, working fluid enters the evaporator through a first, or front row 17, passes through the first row, and exits the condenser through a second, or back row 18. In particular, the working fluid enters the evaporator 19 at the lowest temperature through a collector 24 as shown in FIG. 3. Then the working fluid flows downwards through a tank 20 to a tank 21 through a collector 25, then from tank 21 to a tank 22 in the back row through a collector 26. The working fluid then flows from tank 22 to a tank 23 through a collector 27, and finally exits the evaporator through a collector 28. Air is circulated in a cross-countercurrent arrangement as indicated by the arrow having points 29 and 30, of FIG. 3.

In the embodiments as shown in FIGS. 1, 1A, 2 and 3, the connecting lines between the components of the vapor compression heat transfer system, through which the working fluid may flow, may be constructed of any typical conduit material known for such purpose. In one embodiment, metal piping or metal tubing (such as aluminum or copper or copper alloy tubing) may be used to connect the components of the heat transfer system. In another embodiment, hoses, constructed of various materials, such as polymers or elastomers, or combinations of such materials with reinforcing materials such as metal mesh etc., may be used in the system. One example of a hose design for heat transfer systems, in particular for automobile air conditioning systems, is provided in U.S. Provisional Patent Application No. 60/841,713, filed Sep. 1, 2006 (now International Application PCT/US07/019205 filed Aug. 31, 2007 and published as WO02008-027255A1 on Mar. 6, 2008). For the tubes of the IHX, metal piping or tubing provides more efficient transfer of heat from the hot liquid working fluid to the cold gaseous working fluid.

Various types of compressors may be used in the vapor compression heat transfer system of the embodiments of the present invention, including reciprocating, rotary, jet, centrifugal, scroll, screw or axial-flow, depending on the mechanical means to compress the fluid, or as positive-displacement (e.g., reciprocating, scroll or screw) or dynamic (e.g., centrifugal or jet).

In certain embodiments the heat transfer systems as disclosed herein may employ fin and tube heat exchangers, microchannel heat exchangers and vertical or horizontal single pass tube or plate type heat exchangers, among others for both the evaporator and condenser.

The closed loop vapor compression heat transfer system as described herein may be used in stationary refrigeration, air-conditioning, and heat pumps or mobile air-conditioning and refrigeration systems. Stationary air-conditioning and heat pump applications include window, ductless, ducted, packaged terminal, chillers and light commercial and commercial air-conditioning systems, including packaged rooftop. Refrigeration applications include domestic or home refrigerators and freezers, ice machines, self-contained coolers and freezers, walk-in coolers and freezers and supermarket systems, and transport refrigeration systems.

Mobile refrigeration or mobile air-conditioning systems refer to any refrigeration or air-conditioning system incorporated into a transportation unit for the road, rail, sea or air. In addition, apparatus, which are meant to provide refrigeration or air-conditioning for a system independent of any moving carrier, known as “intermodal” systems, are included in the present invention. Such intermodal systems include “containers” (combined sea/land transport) as well as “swap bodies” (combined road and rail transport). The present invention is particularly useful for road transport refrigerating or air-conditioning apparatus, such as automobile air-conditioning apparatus or refrigerated road transport equipment.

The working fluid utilized in the vapor compression heat transfer system comprises at least one fluoroolefin. By fluoroolefin is meant any compound containing carbon, fluorine and optionally, hydrogen or oxygen that also contains at least one double bond. These fluoroolefins may be linear, branched or cyclic.

Fluoroolefins have a variety of utilities in working fluids, which include use as foaming agents, blowing agents, fire extinguishing agents, heat transfer mediums (such as heat transfer fluids and refrigerants for use in refrigeration systems, refrigerators, air-conditioning systems, heat pumps, chillers, and the like), to name a few.

In some embodiments, heat transfer compositions may comprise fluoroolefins comprising at least one compound with 2 to 12 carbon atoms, in another embodiment the fluoroolefins comprise compounds with 3 to 10 carbon atoms, and in yet another embodiment the fluoroolefins comprise compounds with 3 to 7 carbon atoms. Representative fluoroolefins include but are not limited to all compounds as listed in Table 1, Table 2, and Table 3.

In one embodiment, the present methods use working fluids comprising fluoroolefins having the formula E- or Z—R¹CH═CHR² (Formula I), wherein R¹ and R² are, independently, C₁ to C₆ perfluoroalkyl groups. Examples of R¹ and R² groups include, but are not limited to, CF₃, C₂F₅, CF₂CF₂CF₃, CF(CF₃)₂, CF₂CF₂CF₂CF₃, CF(CF₃)CF₂CF₃, CF₂CF(CF₃)₂, C(CF₃)₃, CF₂CF₂CF₂CF₂CF₃, CF₂CF₂CF(CF₃)₂, C(CF₃)₂C₂F₅, CF₂CF₂CF₂CF₂CF₂CF₃, CF(CF₃) CF₂CF₂C₂F₅, and C(CF₃)₂CF₂C₂F₅. In one embodiment the fluoroolefins of Formula I, have at least about 4 carbon atoms in the molecule. In another embodiment, the fluoroolefins of Formula I have at least about 5 carbon atoms in the molecule. Exemplary, non-limiting Formula I compounds are presented in Table 1.

TABLE 1 Code Structure Chemical Name F11E CF₃CH═CHCF₃ 1,1,1,4,4,4-hexafluorobut-2-ene F12E CF₃CH═CHC₂F₅ 1,1,1,4,4,5,5,5-octafluoropent-2-ene F13E CF₃CH═CHCF₂C₂F₅ 1,1,1,4,4,5,5,6,6,6-decafluorohex-2-ene F13iE CF₃CH═CHCF(CF₃)₂ 1,1,1,4,5,5,5-heptafluoro-4-(trifluoromethyl)pent-2- ene F22E C₂F₅CH═CHC₂F₅ 1,1,1,2,2,5,5,6,6,6-decafluorohex-3-ene F14E CF₃CH═CH(CF₂)₃CF₃ 1,1,1,4,4,5,5,6,6,7,7,7-dodecafluorohept-2-ene F14iE CF₃CH═CHCF₂CF—(CF₃)₂ 1,1,1,4,4,5,6,6,6-nonafluoro-5-(trifluoromethyl)hex-2- ene F14sE CF₃CH═CHCF(CF₃)—C₂F₅ 1,1,1,4,5,5,6,6,6-nonfluoro-4-(trifluoromethyl)hex-2- ene F14tE CF₃CH═CHC(CF₃)₃ 1,1,1,5,5,5-hexafluoro-4,4-bis(trifluoromethyl)pent-2- ene F23E C₂F₅CH═CHCF₂C₂F₅ 1,1,1,2,2,5,5,6,6,7,7,7-dodecafluorohept-3-ene F23iE C₂F₅CH═CHCF(CF₃)₂ 1,1,1,2,2,5,6,6,6-nonafluoro-5-(trifluoromethyl)hex-3- ene F15E CF₃CH═CH(CF₂)₄CF₃ 1,1,1,4,4,5,5,6,6,7,7,8,8,8-tetradecafluorooct-2-ene F15iE CF₃CH═CH—CF₂CF₂CF(CF₃)₂ 1,1,1,4,4,5,5,6,7,7,7-undecafluoro-6- (trifluoromethyl)hept-2-ene F15tE CF₃CH═CH—C(CF₃)₂C₂F₅ 1,1,1,5,5,6,6,6-octafluoro-4,4-bis(trifluoromethyl)hex- 2-ene F24E C₂F₅CH═CH(CF₂)₃CF₃ 1,1,1,2,2,5,5,6,6,7,7,8,8,8-tetradecafluorooct-3-ene F24iE C₂F₅CH═CHCF₂CF—(CF₃)₂ 1,1,1,2,2,5,5,6,7,7,7-undecafluoro-6- (trifluoromethyl)hept-3-ene F24sE C₂F₅CH═CHCF(CF₃)—C₂F₅ 1,1,1,2,2,5,6,6,7,7,7-undecafluoro-5- (trifluoromethyl)hept-3-ene F24tE C₂F₅CH═CHC(CF₃)₃ 1,1,1,2,2,6,6,6-octafluoro-5,5-bis(trifluoromethyl)hex- 3-ene F33E C₂F₅CF₂CH═CH—CF₂C₂F₅ 1,1,1,2,2,3,3,6,6,7,7,8,8,8-tetradecafluorooct-4-ene F3i3iE (CF₃)₂CFCH═CH—CF(CF₃)₂ 1,1,1,2,5,6,6,6-octafluoro-2,5-bis(trifluoromethyl)hex- 3-ene F33iE C₂F₅CF₂CH═CH—CF(CF₃)₂ 1,1,1,2,5,5,6,6,7,7,7-undecafluoro-2- (trifluoromethyl)hept-3-ene F16E CF₃CH═CH(CF₂)₅CF₃ 1,1,1,4,4,5,5,6,6,7,7,8,8,,9,9,9-hexadecafluoronon-2- ene F16sE CF₃CH═CHCF(CF₃)(CF₂)₂C₂F₅ 1,1,1,4,5,5,6,6,7,7,8,8,8-tridecafluoro-4- (trifluoromethyl)hept-2-ene F16tE CF₃CH═CHC(CF₃)₂CF₂C₂F₅ 1,1,1,6,6,6-octafluoro-4,4-bis(trifluoromethyl)hept-2- ene F25E C₂F₅CH═CH(CF₂)₄CF₃ 1,1,1,2,2,5,5,6,6,7,7,8,8,9,9,9-hexadecafluoronon-3- ene F25iE C₂F₅CH═CH—CF₂CF₂CF(CF₃)₂ 1,1,1,2,2,5,5,6,6,7,8,8,8-tridecafluoro-7- (trifluoromethyl)oct-3-ene F25tE C₂F₅CH═CH—C(CF₃)₂C₂F₅ 1,1,1,2,2,6,6,7,7,7-decafluoro-5,5- bis(trifluoromethyl)hept-3-ene F34E C₂F₅CF₂CH═CH—(CF₂)₃CF₃ 1,1,1,2,2,3,3,6,6,7,7,8,8,9,9,9-hexadecafluoronon-4- ene F34iE C₂F₅CF₂CH═CH—CF₂CF(CF₃)₂ 1,1,1,2,2,3,3,6,6,7,8,8,8-tridecafluoro-7- (trifluoromethyl)oct-4-ene F34sE C₂F₅CF₂CH═CH—CF(CF₃)C₂F₅ 1,1,1,2,2,3,3,6,7,7,8,8,8-tridecafluoro-6- (trifluoromethyl)oct-4-ene F34tE C₂F₅CF₂CH═CH—C(CF₃)₃ 1,1,1,5,5,6,6,7,7,7-decafluoro-2,2- bis(trifluoromethyl)hept-3-ene F3i4E (CF₃)₂CFCH═CH—(CF₂)₃CF₃ 1,1,1,2,5,5,6,6,7,7,8,8,8-tridecafluoro- 2(trifluoromethyl)oct-3-ene F3i4iE (CF₃)₂CFCH═CH—CF₂CF(CF₃)₂ 1,1,1,2,5,5,6,7,7,7-decafluoro-2,6- bis(trifluoromethyl)hept-3-ene F3i4sE (CF₃)₂CFCH═CH—CF(CF₃)C₂F₅ 1,1,1,2,5,6,6,7,7,7-decafluoro-2,5- bis(trifluoromethyl)hept-3-ene F3i4tE (CF₃)₂CFCH═CH—C(CF₃)₃ 1,1,1,2,6,6,6-heptafluoro-2,5,5- tris(trifluoromethyl)hex-3-ene F26E C₂F₅CH═CH(CF₂)₅CF₃ 1,1,1,2,2,5,5,6,6,7,7,8,8,9,9,10,10,10- octadecafluorodec-3-ene F26sE C₂F₅CH═CHCF(CF₃)(CF₂)₂C₂F₅ 1,1,1,2,2,5,6,6,7,7,8,8,9,9,9-pentadecafluoro-5- (trifluoromethyl)non-3-ene F26tE C₂F₅CH═CHC(CF₃)₂CF₂C₂F₅ 1,1,1,2,2,6,6,7,7,8,8,8-dodecafluoro-5,5- bis(trifluoromethyl)oct-3-ene F35E C₂F₅CF₂CH═CH—(CF₂)₄CF₃ 1,1,1,2,2,3,3,6,6,7,7,8,8,9,9,10,10,10- octadecafluorodec-4-ene F35iE C₂F₅CF₂CH═CH—CF₂CF₂CF(CF₃)₂ 1,1,1,2,2,3,3,6,6,7,7,8,9,9,9-pentadecafluoro-8- (trifluoromethyl)non-4-ene F35tE C₂F₅CF₂CH═CH—C(CF₃)₂C₂F₅ 1,1,1,2,2,3,3,7,7,8,8,8-dodecafluoro-6,6- bis(trifluoromethyl)oct-4-ene F3i5E (CF₃)₂CFCH═CH—(CF₂)₄CF₃ 1,1,1,2,5,5,6,6,7,7,8,8,9,9,9-pentadecafluoro-2- (trifluoromethyl)non-3-ene F3i5iE (CF₃)₂CFCH═CH—CF₂CF₂CF(CF₃)₂ 1,1,1,2,5,5,6,6,7,8,8,8-dodecafluoro-2,7- bis(trifluoromethyl)oct-3-ene F3i5tE (CF₃)₂CFCH═CH—C(CF₃)₂C₂F₅ 1,1,1,2,6,6,7,7,7-nonafluoro-2,5,5- tris(trifluoromethyl)hept-3-ene F44E CF₃(CF₂)₃CH═CH—(CF₂)₃CF₃ 1,1,1,2,2,3,3,4,4,7,7,8,8,9,9,10,10,10- octadecafluorodec-5-ene F44iE CF₃(CF₂)₃CH═CH—CF₂CF(CF₃)₂ 1,1,1,2,3,3,6,6,7,7,8,8,9,9,9-pentadecafluoro-2- (trifluoromethyl)non-4-ene F44sE CF₃(CF₂)₃CH═CH—CF(CF₃)C₂F₅ 1,1,1,2,2,3,6,6,7,7,8,8,9,9,9-pentadecafluoro-3- (trifluoromethyl)non-4-ene F44tE CF₃(CF₂)₃CH═CH—C(CF₃)₃ 1,1,1,5,5,6,6,7,7,8,8,8-dodecafluoro-2,2,- bis(trifluoromethyl)oct-3-ene F4i4iE (CF₃)₂CFCF₂CH═CH—CF₂CF(CF₃)₂ 1,1,1,2,3,3,6,6,7,8,8,8-dodecafluoro-2,7- bis(trifluoromethyl)oct-4-ene F4i4sE (CF₃)₂CFCF₂CH═CH—CF(CF₃)C₂F₅ 1,1,1,2,3,3,6,7,7,8,8,8-dodecafluoro-2,6- bis(trifluoromethyl)oct-4-ene F4i4tE (CF₃)₂CFCF₂CH═CH—C(CF₃)₃ 1,1,1,5,5,6,7,7,7-nonafluoro-2,2,6- tris(trifluoromethyl)hept-3-ene F4s4sE C₂F₅CF(CF₃)CH═CH—CF(CF₃)C₂F₅ 1,1,1,2,2,3,6,7,7,8,8,8-dodecafluoro-3,6- bis(trifluoromethyl)oct-4-ene F4s4tE C₂F₅CF(CF₃)CH═CH—C(CF₃)₃ 1,1,1,5,6,6,7,7,7-nonafluoro-2,2,5- tris(trifluoromethyl)hept-3-ene F4t4tE (CF₃)₃CCH═CH—C(CF₃)₃ 1,1,1,6,6,6-hexafluoro-2,2,5,5- tetrakis(trifluoromethyl)hex-3-ene

Compounds of Formula I may be prepared by contacting a perfluoroalkyl iodide of the formula R¹I with a perfluoroalkyltrihydroolefin of the formula R²CH═CH₂ to form a trihydroiodoperfluoroalkane of the formula R¹CH₂CHIR². This trihydroiodoperfluoroalkane can then be dehydroiodinated to form R¹CH═CHR². Alternatively, the olefin R¹CH═CHR² may be prepared by dehydroiodination of a trihydroiodoperfluoroalkane of the formula R¹CHICH₂R² formed in turn by reacting a perfluoroalkyl iodide of the formula R²I with a perfluoroalkyltrihydroolefin of the formula R¹CH═CH₂.

Said contacting of a perfluoroalkyl iodide with a perfluoroalkyltrihydroolefin may take place in batch mode by combining the reactants in a suitable reaction vessel capable of operating under the autogenous pressure of the reactants and products at reaction temperature. Suitable reaction vessels include fabricated from stainless steels, in particular of the austenitic type, and the well-known high nickel alloys such as Monel® nickel-copper alloys, Hastelloy® nickel based alloys and Inconel® nickel-chromium alloys.

Alternatively, the reaction may take be conducted in semi-batch mode in which the perfluoroalkyltrihydroolefin reactant is added to the perfluoroalkyl iodide reactant by means of a suitable addition apparatus such as a pump at the reaction temperature.

The ratio of perfluoroalkyl iodide to perfluoroalkyltrihydroolefin should be between about 1:1 to about 4:1, preferably from about 1.5:1 to 2.5:1. Ratios less than 1.5:1 tend to result in large amounts of the 2:1 adduct as reported by Jeanneaux, et. al. in Journal of Fluorine Chemistry, Vol. 4, pages 261-270 (1974).

Preferred temperatures for contacting of said perfluoroalkyl iodide with said perfluoroalkyltrihydroolefin are preferably within the range of about 150° C. to 300° C., preferably from about 170° C. to about 250° C., and most preferably from about 180° C. to about 230° C.

Suitable contact times for the reaction of the perfluoroalkyl iodide with the perfluoroalkyltrihydroolefin are from about 0.5 hour to 18 hours, preferably from about 4 to about 12 hours.

The trihydroiodoperfluoroalkane prepared by reaction of the perfluoroalkyl iodide with the perfluoroalkyltrihydroolefin may be used directly in the dehydroiodination step or may preferably be recovered and purified by distillation prior to the dehydroiodination step.

The dehydroiodination step is carried out by contacting the trihydroiodoperfluoroalkane with a basic substance. Suitable basic substances include alkali metal hydroxides (e.g., sodium hydroxide or potassium hydroxide), alkali metal oxide (for example, sodium oxide), alkaline earth metal hydroxides (e.g., calcium hydroxide), alkaline earth metal oxides (e.g., calcium oxide), alkali metal alkoxides (e.g., sodium methoxide or sodium ethoxide), aqueous ammonia, sodium amide, or mixtures of basic substances such as soda lime. Preferred basic substances are sodium hydroxide and potassium hydroxide.

Said contacting of the trihydroiodoperfluoroalkane with a basic substance may take place in the liquid phase preferably in the presence of a solvent capable of dissolving at least a portion of both reactants. Solvents suitable for the dehydroiodination step include one or more polar organic solvents such as alcohols (e.g., methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, and tertiary butanol), nitriles (e.g., acetonitrile, propionitrile, butyronitrile, benzonitrile, or adiponitrile), dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, or sulfolane. The choice of solvent may depend on the boiling point product and the ease of separation of traces of the solvent from the product during purification. Typically, ethanol or isopropanol are good solvents for the reaction.

Typically, the dehydroiodination reaction may be carried out by addition of one of the reactants (either the basic substance or the trihydroiodoperfluoroalkane) to the other reactant in a suitable reaction vessel. Said reaction may be fabricated from glass, ceramic, or metal and is preferably agitated with an impeller or stirring mechanism.

Temperatures suitable for the dehydroiodination reaction are from about 10° C. to about 100° C., preferably from about 200° C. to about 70° C. The dehydroiodination reaction may be carried out at ambient pressure or at reduced or elevated pressure. Of note are dehydroiodination reactions in which the compound of Formula I is distilled out of the reaction vessel as it is formed.

Alternatively, the dehydroiodination reaction may be conducted by contacting an aqueous solution of said basic substance with a solution of the trihydroiodoperfluoroalkane in one or more organic solvents of lower polarity such as an alkane (e.g., hexane, heptane, or octane), aromatic hydrocarbon (e.g., toluene), halogenated hydrocarbon (e.g., methylene chloride, chloroform, carbon tetrachloride, or perchloroethylene), or ether (e.g., diethyl ether, methyl tert-butyl ether, tetrahydrofuran, 2-methyl tetrahydrofuran, dioxane, dimethoxyethane, diglyme, or tetraglyme) in the presence of a phase transfer catalyst. Suitable phase transfer catalysts include quaternary ammonium halides (e.g., tetrabutylammonium bromide, tetrabutylammonium hydrosulfate, triethylbenzylammonium chloride, dodecyltrimethylammonium chloride, and tricaprylylmethylammonium chloride), quaternary phosphonium halides (e.g., triphenylmethylphosphonium bromide and tetraphenylphosphonium chloride), or cyclic polyether compounds known in the art as crown ethers (e.g., 18-crown-6 and 15-crown-5).

Alternatively, the dehydroiodination reaction may be conducted in the absence of solvent by adding the trihydroiodoperfluoroalkane to a solid or liquid basic substance.

Suitable reaction times for the dehydroiodination reactions are from about 15 minutes to about six hours or more depending on the solubility of the reactants. Typically the dehydroiodination reaction is rapid and requires about 30 minutes to about three hours for completion. The compound of formula I may be recovered from the dehydroiodination reaction mixture by phase separation after addition of water, by distillation, or by a combination thereof.

In another embodiment of the present invention, fluoroolefins comprise cyclic fluoroolefins (cyclo-[CX═CY(CZW)_(n)—] (Formula II), wherein X, Y, Z, and W are independently selected from H and F, and n is an integer from 2 to 5). In one embodiment the fluoroolefins of Formula II, have at least about 3 carbon atoms in the molecule. In another embodiment, the fluoroolefins of Formula II have at least about 4 carbon atoms in the molecule. In yet another embodiment, the fluoroolefins of Formula II have at least about 5 carbon atoms in the molecule. Representative cyclic fluoroolefins of Formula II are listed in Table 2.

TABLE 2 Cyclic fluoroolefins Structure Chemical name FC-C1316cc cyclo-CF₂CF₂CF═CF— 1,2,3,3,4,4-hexafluorocyclobutene HFC-C1334cc cyclo-CF₂CF₂CH═CH— 3,3,4,4-tetrafluorocyclobutene HFC-C1436 cyclo-CF₂CF₂CF₂CH═CH— 3,3,4,4,5,5,-hexafluorocyclopentene FC-C1418y cyclo-CF₂CF═CFCF₂CF₂— 1,2,3,3,4,4,5,5-octafluorocyclopentene FC-C151-10y cyclo-CF₂CF═CFCF₂CF₂CF₂— 1,2,3,3,4,4,5,5,6,6- decafluorocyclohexene

The compositions of the present invention may comprise a single compound of Formula I or formula II, for example, one of the compounds in Table 1 or Table 2, or may comprise a combination of compounds of Formula I or formula II.

In another embodiment, fluoroolefins may comprise those compounds listed in Table 3.

TABLE 3 Name Structure Chemical name HFC-1225ye CF₃CF═CHF 1,2,3,3,3-pentafluoro-1-propene HFC-1225zc CF₃CH═CF₂ 1,1,3,3,3-pentafluoro-1-propene HFC-1225yc CHF₂CF═CF₂ 1,1,2,3,3-pentafluoro-1-propene HFC-1234ye CHF₂CF═CHF 1,2,3,3-tetrafluoro-1-propene HFC-1234yf CF₃CF═CH₂ 2,3,3,3-tetrafluoro-1-propene HFC-1234ze CF₃CH═CHF 1,3,3,3-tetrafluoro-1-propene HFC-1234yc CH₂FCF═CF₂ 1,1,2,3-tetrafluoro-1-propene HFC-1234zc CHF₂CH═CF₂ 1,1,3,3-tetrafluoro-1-propene HFC-1243yf CHF₂CF═CH₂ 2,3,3-trifluoro-1-propene HFC-1243zf CF₃CH═CH₂ 3,3,3-trifluoro-1-propene HFC-1243yc CH₃CF═CF₂ 1,1,2-trifluoro-1-propene HFC-1243zc CH₂FCH═CF₂ 1,1,3-trifluoro-1-propene HFC-1243ye CH₂FCF═CHF 1,2,3-trifluoro-1-propene HFC-1243ze CHF₂CH═CHF 1,3,3-trifluoro-1-propene FC-1318my CF₃CF═CFCF₃ 1,1,1,2,3,4,4,4-octafluoro-2-butene FC-1318cy CF₃CF₂CF═CF₂ 1,1,2,3,3,4,4,4-octafluoro-1-butene HFC-1327my CF₃CF═CHCF₃ 1,1,1,2,4,4,4-heptafluoro-2-butene HFC-1327ye CHF═CFCF₂CF₃ 1,2,3,3,4,4,4-heptafluoro-1-butene HFC-1327py CHF₂CF═CFCF₃ 1,1,1,2,3,4,4-heptafluoro-2-butene HFC-1327et (CF₃)₂C═CHF 1,3,3,3-tetrafluoro-2-(trifluoromethyl)-1- propene HFC-1327cz CF₂═CHCF₂CF₃ 1,1,3,3,4,4,4-heptafluoro-1-butene HFC-1327cye CF₂═CFCHFCF₃ 1,1,2,3,4,4,4-heptafluoro-1-butene HFC-1327cyc CF₂═CFCF₂CHF₂ 1,1,2,3,3,4,4-heptafluoro-1-butene HFC-1336yf CF₃CF₂CF═CH₂ 2,3,3,4,4,4-hexafluoro-1-butene HFC-1336ze CHF═CHCF₂CF₃ 1,3,3,4,4,4-hexafluoro-1-butene HFC-1336eye CHF═CFCHFCF₃ 1,2,3,4,4,4-hexafluoro-1-butene HFC-1336eyc CHF═CFCF₂CHF₂ 1,2,3,3,4,4-hexafluoro-1-butene HFC-1336pyy CHF₂CF═CFCHF₂ 1,1,2,3,4,4-hexafluoro-2-butene HFC-1336qy CH₂FCF═CFCF₃ 1,1,1,2,3,4-hexafluoro-2-butene HFC-1336pz CHF₂CH═CFCF₃ 1,1,1,2,4,4-hexafluoro-2-butene HFC-1336mzy CF₃CH═CFCHF₂ 1,1,1,3,4,4-hexafluoro-2-butene HFC-1336qc CF₂═CFCF₂CH₂F 1,1,2,3,3,4-hexafluoro-1-butene HFC-1336pe CF₂═CFCHFCHF₂ 1,1,2,3,4,4-hexafluoro-1-butene HFC-1336ft CH₂═C(CF₃)₂ 3,3,3-trifluoro-2-(trifluoromethyl)-1-propene HFC-1345qz CH₂FCH═CFCF₃ 1,1,1,2,4-pentafluoro-2-butene HFC-1345mzy CF₃CH═CFCH₂F 1,1,1,3,4-pentafluoro-2-butene HFC-1345fz CF₃CF₂CH═CH₂ 3,3,4,4,4-pentafluoro-1-butene HFC-1345mzz CHF₂CH═CHCF₃ 1,1,1,4,4-pentafluoro-2-butene HFC-1345sy CH₃CF═CFCF₃ 1,1,1,2,3-pentafluoro-2-butene HFC-1345fyc CH₂═CFCF₂CHF₂ 2,3,3,4,4-pentafluoro-1-butene HFC-1345pyz CHF₂CF═CHCHF₂ 1,1,2,4,4-pentafluoro-2-butene HFC-1345cyc CH₃CF₂CF═CF₂ 1,1,2,3,3-pentafluoro-1-butene HFC-1345pyy CH₂FCF═CFCHF₂ 1,1,2,3,4-pentafluoro-2-butene HFC-1345eyc CH₂FCF₂CF═CHF 1,2,3,3,4-pentafluoro-1-butene HFC-1345ctm CF₂═C(CF₃)(CH₃) 1,1,3,3,3-pentafluoro-2-methyl-1-propene HFC-1345ftp CH₂═C(CHF₂)(CF₃) 2-(difluoromethyl)-3,3,3-trifluoro-1-propene HFC1345fye CH₂═CFCHFCF₃ 2,3,4,4,4-pentafluoro-1-butene HFC-1345eyf CHF═CFCH₂CF₃ 1,2,4,4,4-pentafluoro-1-butene HFC-1345eze CHF═CHCHFCF₃ 1,3,4,4,4-pentafluoro-1-butene HFC-1345ezc CHF═CHCF₂CHF₂ 1,3,3,4,4-pentafluoro-1-butene HFC-1345eye CHF═CFCHFCHF₂ 1,2,3,4,4-pentafluoro-1-butene HFC-1354fzc CH₂═CHCF₂CHF₂ 3,3,4,4-tetrafluoro-1-butene HFC-1354ctp CF₂═C(CHF₂)(CH₃) 1,1,3,3-tetrafluoro-2-methyl-1-propene HFC-1354etm CHF═C(CF₃)(CH₃) 1,3,3,3-tetrafluoro-2-methyl-1-propene HFC-1354tfp CH₂═C(CHF₂)₂ 2-(difluoromethyl)-3,3-difluoro-1-propene HFC-1354my CF₃CF═CHCH₃ 1,1,1,2-tetrafluoro-2-butene HFC-1354mzy CH₃CF═CHCF₃ 1,1,1,3-tetrafluoro-2-butene FC-141-10myy CF₃CF═CFCF₂CF₃ 1,1,1,2,3,4,4,5,5,5-decafluoro-2-pentene FC-141-10cy CF₂═CFCF₂CF₂CF₃ 1,1,2,3,3,4,4,5,5,5-decafluoro-1-pentene HFC-1429mzt (CF₃)₂C═CHCF₃ 1,1,1,4,4,4-hexafluoro-2-(trifluoromethyl)-2- butene HFC-1429myz CF₃CF═CHCF₂CF₃ 1,1,1,2,4,4,5,5,5-nonafluoro-2-pentene HFC-1429mzy CF₃CH═CFCF₂CF₃ 1,1,1,3,4,4,5,5,5-nonafluoro-2-pentene HFC-1429eyc CHF═CFCF₂CF₂CF₃ 1,2,3,3,4,4,5,5,5-nonafluoro-1-pentene HFC-1429czc CF₂═CHCF₂CF₂CF₃ 1,1,3,3,4,4,5,5,5-nonafluoro-1-pentene HFC-1429cycc CF₂═CFCF₂CF₂CHF₂ 1,1,2,3,3,4,4,5,5-nonafluoro-1-pentene HFC-1429pyy CHF₂CF═CFCF₂CF₃ 1,1,2,3,4,4,5,5,5-nonafluoro-2-pentene HFC-1429myyc CF₃CF═CFCF₂CHF₂ 1,1,1,2,3,4,4,5,5-nonafluoro-2-pentene HFC-1429myye CF₃CF═CFCHFCF₃ 1,1,1,2,3,4,5,5,5-nonafluoro-2-pentene HFC-1429eyym CHF═CFCF(CF₃)₂ 1,2,3,4,4,4-hexafluoro-3-(trifluoromethyl)-1- butene HFC-1429cyzm CF₂═CFCH(CF₃)₂ 1,1,2,4,4,4-hexafluoro-3-(trifluoromethyl)-1- butene HFC-1429mzt CF₃CH═C(CF₃)₂ 1,1,1,4,4,4-hexafluoro-2-(trifluoromethyl)-2- butene HFC-1429czym CF₂═CHCF(CF₃)₂ 1,1,3,4,4,4-hexafluoro-3-(trifluoromethyl)-1- butene HFC-1438fy CH₂═CFCF₂CF₂CF₃ 2,3,3,4,4,5,5,5-octafluoro-1-pentene HFC-1438eycc CHF═CFCF₂CF₂CHF₂ 1,2,3,3,4,4,5,5-octafluoro-1-pentene HFC-1438ftmc CH₂═C(CF₃)CF₂CF₃ 3,3,4,4,4-pentafluoro-2-(trifluoromethyl)-1- butene HFC-1438czzm CF₂═CHCH(CF₃)₂ 1,1,4,4,4-pentafluoro-3-(trifluoromethyl)-1- butene HFC-1438ezym CHF═CHCF(CF₃)₂ 1,3,4,4,4-pentafluoro-3-(trifluoromethyl)-1- butene HFC-1438ctmf CF₂═C(CF₃)CH₂CF₃ 1,1,4,4,4-pentafluoro-2-(trifluoromethyl)-1- butene HFC-1447fzy (CF₃)₂CFCH═CH₂ 3,4,4,4-tetrafluoro-3-(trifluoromethyl)-1- butene HFC-1447fz CF₃CF₂CF₂CH═CH₂ 3,3,4,4,5,5,5-heptafluoro-1-pentene HFC-1447fycc CH₂═CFCF₂CF₂CHF₂ 2,3,3,4,4,5,5-heptafluoro-1-pentene HFC-1447czcf CF₂═CHCF₂CH₂CF₃ 1,1,3,3,5,5,5-heptafluoro-1-pentene HFC-1447mytm CF₃CF═C(CF₃)(CH₃) 1,1,1,2,4,4,4-heptafluoro-3-methyl-2- butene HFC-1447fyz CH₂═CFCH(CF₃)₂ 2,4,4,4-tetrafluoro-3-(trifluoromethyl)-1- butene HFC-1447ezz CHF═CHCH(CF₃)₂ 1,4,4,4-tetrafluoro-3-(trifluoromethyl)-1- butene HFC-1447qzt CH₂FCH═C(CF₃)₂ 1,4,4,4-tetrafluoro-2-(trifluoromethyl)-2- butene HFC-1447syt CH₃CF═C(CF₃)₂ 2,4,4,4-tetrafluoro-2-(trifluoromethyl)-2- butene HFC-1456szt (CF₃)₂C═CHCH₃ 3-(trifluoromethyl)-4,4,4-trifluoro-2-butene HFC-1456szy CF₃CF₂CF═CHCH₃ 3,4,4,5,5,5-hexafluoro-2-pentene HFC-1456mstz CF₃C(CH₃)═CHCF₃ 1,1,1,4,4,4-hexafluoro-2-methyl-2-butene HFC-1456fzce CH₂═CHCF₂CHFCF₃ 3,3,4,5,5,5-hexafluoro-1-pentene HFC-1456ftmf CH₂═C(CF₃)CH₂CF₃ 4,4,4-trifluoro-2-(trifluoromethyl)-1-butene FC-151-12c CF₃(CF₂)₃CF═CF₂ 1,1,2,3,3,4,4,5,5,6,6,6-dodecafluoro-1- hexene (or perfluoro-1-hexene) FC-151-12mcy CF₃CF₂CF═CFCF₂CF₃ 1,1,1,2,2,3,4,5,5,6,6,6-dodecafluoro-3- hexene (or perfluoro-3-hexene) FC-151-12mmtt (CF₃)₂C═C(CF₃)₂ 1,1,1,4,4,4-hexafluoro-2,3- bis(trifluoromethyl)-2-butene FC-151-12mmzz (CF₃)₂CFCF═CFCF₃ 1,1,1,2,3,4,5,5,5-nonafluoro-4- (trifluoromethyl)-2-pentene HFC-152-11mmtz (CF₃)₂C═CHC₂F₅ 1,1,1,4,4,5,5,5-octafluoro-2- (trifluoromethyl)-2-pentene HFC-152- (CF₃)₂CFCF═CHCF₃ 1,1,1,3,4,5,5,5-octafluoro-4- 11mmyyz (trifluoromethyl)-2-pentene PFBE CF₃CF₂CF₂CF₂CH═CH₂ 3,3,4,4,5,5,6,6,6-nonafluoro-1-hexene (or (or HFC-1549fz) perfluorobutylethylene) HFC-1549fztmm CH₂═CHC(CF₃)₃ 4,4,4-trifluoro-3,3-bis(trifluoromethyl)-1- butene HFC-1549mmtts (CF₃)₂C═C(CH₃)(CF₃) 1,1,1,4,4,4-hexafluoro-3-methyl-2- (trifluoromethyl)-2-butene HFC-1549fycz CH₂═CFCF₂CH(CF₃)₂ 2,3,3,5,5,5-hexafluoro-4-(trifluoromethyl)-1- pentene HFC-1549myts CF₃CF═C(CH₃)CF₂CF₃ 1,1,1,2,4,4,5,5,5-nonafluoro-3-methyl-2- pentene HFC-1549mzzz CF₃CH═CHCH(CF₃)₂ 1,1,1,5,5,5-hexafluoro-4-(trifluoromethyl)-2- pentene HFC-1558szy CF₃CF₂CF₂CF═CHCH₃ 3,4,4,5,5,6,6,6-octafluoro-2-hexene HFC-1558fzccc CH₂═CHCF₂CF₂CF₂CHF₂ 3,3,4,4,5,5,6,6-octafluoro-2-hexene HFC-1558mmtzc (CF₃)₂C═CHCF₂CH₃ 1,1,1,4,4-pentafluoro-2-(trifluoromethyl)-2- pentene HFC-1558ftmf CH₂═C(CF₃)CH₂C₂F₅ 4,4,5,5,5-pentafluoro-2-(trifluoromethyl)-1- pentene HFC-1567fts CF₃CF₂CF₂C(CH₃)═CH₂ 3,3,4,4,5,5,5-heptafluoro-2-methyl-1- pentene HFC-1567szz CF₃CF₂CF₂CH═CHCH₃ 4,4,5,5,6,6,6-heptafluoro-2-hexene HFC-1567fzfc CH₂═CHCH₂CF₂C₂F₅ 4,4,5,5,6,6,6-heptafluoro-1-hexene HFC-1567sfyy CF₃CF₂CF═CFC₂H₅ 1,1,1,2,2,3,4-heptafluoro-3-hexene HFC-1567fzfy CH₂═CHCH₂CF(CF₃)₂ 4,5,5,5-tetrafluoro-4-(trifluoromethyl)-1- pentene HFC-1567myzzm CF₃CF═CHCH(CF₃)(CH₃) 1,1,1,2,5,5,5-heptafluoro-4-methyl-2- pentene HFC-1567mmtyf (CF₃)₂C═CFC₂H₅ 1,1,1,3-tetrafluoro-2-(trifluoromethyl)-2- pentene FC-161-14myy CF₃CF═CFCF₂CF₂C₂F₅ 1,1,1,2,3,4,4,5,5,6,6,7,7,7-tetradecafluoro- 2-heptene FC-161-14mcyy CF₃CF₂CF═CFCF₂C₂F₅ 1,1,1,2,2,3,4,5,5,6,6,7,7,7-tetradecafluoro- 2-heptene HFC-162-13mzy CF₃CH═CFCF₂CF₂C₂F₅ 1,1,1,3,4,4,5,5,6,6,7,7,7-tridecafluoro-2- heptene HFC162-13myz CF₃CF═CHCF₂CF₂C₂F₅ 1,1,1,2,4,4,5,5,6,6,7,7,7-tridecafluoro-2- heptene HFC-162-13mczy CF₃CF₂CH═CFCF₂C₂F₅ 1,1,1,2,2,4,5,5,6,6,7,7,7-tridecafluoro-3- heptene HFC-162-13mcyz CF₃CF₂CF═CHCF₂C₂F₅ 1,1,1,2,2,3,5,5,6,6,7,7,7-tridecafluoro-3- heptene PEVE CF₂═CFOCF₂CF₃ pentafluoroethyl trifluorovinyl ether PMVE CF₂═CFOCF₃ trifluoromethyl trifluorovinyl ether

The compounds listed in Table 2 and Table 3 are available commercially or may be prepared by processes known in the art or as described herein.

1,1,1,4,4-pentafluoro-2-butene may be prepared from 1,1,1,2,4,4-hexafluorobutane (CHF₂CH₂CHFCF₃) by dehydrofluorination over solid KOH in the vapor phase at room temperature. The synthesis of 1,1,1,2,4,4-hexafluorobutane is described in U.S. Pat. No. 6,066,768, incorporated herein by reference.

1,1,1,4,4,4-hexafluoro-2-butene may be prepared from 1,1,1,4,4,4-hexafluoro-2-iodobutane (CF₃CHICH₂CF₃) by reaction with KOH using a phase transfer catalyst at about 60° C. The synthesis of 1,1,1,4,4,4-hexafluoro-2-iodobutane may be carried out by reaction of perfluoromethyl iodide (CF₃I) and 3,3,3-trifluoropropene (CF₃CH═CH₂) at about 200° C. under autogenous pressure for about 8 hours.

3,4,4,5,5,5-hexafluoro-2-pentene may be prepared by dehydrofluorination of 1,1,1,2,2,3,3-heptafluoropentane (CF₃CF₂CF₂CH₂CH₃) using solid KOH or over a carbon catalyst at 200-300° C. 1,1,1,2,2,3,3-heptafluoropentane may be prepared by hydrogenation of 3,3,4,4,5,5,5-heptafluoro-1-pentene (CF₃CF₂CF₂CH═CH₂).

1,1,1,2,3,4-hexafluoro-2-butene may be prepared by dehydrofluorination of 1,1,1,2,3,3,4-heptafluorobutane (CH₂FCF₂CHFCF₃) using solid KOH.

1,1,1,2,4,4-hexafluoro-2-butene may be prepared by dehydrofluorination of 1,1,1,2,2,4,4-heptafluorobutane (CHF₂CH₂CF₂CF₃) using solid KOH.

1,1,1,3,4,4-hexafluoro2-butene may be prepared by dehydrofluorination of 1,1,1,3,3,4,4-heptafluorobutane (CF₃CH₂CF₂CHF₂) using solid KOH.

1,1,1,2,4-pentafluoro-2-butene may be prepared by dehydrofluorination of 1,1,1,2,2,3-hexafluorobutane (CH₂FCH₂CF₂CF₃) using solid KOH.

1,1,1,3,4-pentafluoro-2-butene may be prepared by dehydrofluorination of 1,1,1,3,3,4-hexafluorobutane (CF₃CH₂CF₂CH₂F) using solid KOH.

1,1,1,3-tetrafluoro-2-butene may be prepared by reacting 1,1,1,3,3-pentafluorobutane (CF₃CH₂CF₂CH₃) with aqueous KOH at 120° C.

1,1,1,4,4,5,5,5-octafluoro-2-pentene may be prepared from (CF₃CHICH₂CF₂CF₃) by reaction with KOH using a phase transfer catalyst at about 60° C. The synthesis of 4-iodo-1,1,1,2,2,5,5,5-octafluoropentane may be carried out by reaction of perfluoroethyliodide (CF₃CF₂I) and 3,3,3-trifluoropropene at about 200° C. under autogenous pressure for about 8 hours.

1,1,1,2,2,5,5,6,6,6-decafluoro-3-hexene may be prepared from 1,1,1,2,2,5,5,6,6,6-decafluoro-3-iodohexane (CF₃CF₂CHICH₂CF₂CF₃) by reaction with KOH using a phase transfer catalyst at about 60° C. The synthesis of 1,1,1,2,2,5,5,6,6,6-decafluoro-3-iodohexane may be carried out by reaction of perfluoroethyliodide (CF₃CF₂I) and 3,3,4,4,4-pentafluoro-1-butene (CF₃CF₂CH═CH₂) at about 200° C. under autogenous pressure for about 8 hours.

1,1,1,4,5,5,5-heptafluoro-4-(trifluoromethyl)-2-pentene may be prepared by the dehydrofluorination of 1,1,1,2,5,5,5-heptafluoro-4-iodo-2-(trifluoromethyl)-pentane (CF₃CHICH₂CF(CF₃)₂) with KOH in isopropanol. CF₃CHICH₂CF(CF₃)₂ is made from reaction of (CF₃)₂CFI with CF₃CH═CH₂ at high temperature, such as about 200° C.

1,1,1,4,4,5,5,6,6,6-decafluoro-2-hexene may be prepared by the reaction of 1,1,1,4,4,4-hexafluoro-2-butene (CF₃CH═CHCF₃) with tetrafluoroethylene (CF₂═CF₂) and antimony pentafluoride (SbF₅).

2,3,3,4,4-pentafluoro-1-butene may be prepared by dehydrofluorination of 1,1,2,2,3,3-hexafluorobutane over fluorided alumina at elevated temperature.

2,3,3,4,4,5,5,5-ocatafluoro-1-pentene may be prepared by dehydroflurination of 2,2,3,3,4,4,5,5,5-nonafluoropentane over solid KOH. 1,2,3,3,4,4,5,5-octafluoro-1-pentene may be prepared by dehydrofluorination of 2,2,3,3,4,4,5,5,5-nonafluoropentane over fluorided alumina at elevated temperature.

Many of the compounds of Formula I, Formula II, Table 1, Table 2, and Table 3 exist as different configurational isomers or stereoisomers. When the specific isomer is not designated, the described composition is intended to include all single configurational isomers, single stereoisomers, or any combination thereof. For instance, F11E is meant to represent the E-isomer, Z-isomer, or any combination or mixture of both isomers in any ratio. As another example, HFC-1225ye is meant to represent the E-isomer, Z-isomer, or any combination or mixture of both isomers in any ratio, with the Z isomer preferred.

In some embodiments, the working fluid may further comprise at least one compound selected from hydrofluorocarbons, fluoroethers, hydrocarbons, dimethyl ether (DME), carbon dioxide (CO₂), ammonia (NH₃), and iodotrifluoromethane (CF₃I).

In some embodiments, the working fluid may further comprise hydrofluorocarbons comprising at least one saturated compound containing carbon, hydrogen, and fluorine. Of particular utility are hydrofluorocarbons having 1 to 7 carbon atoms and having a normal boiling point of from about −90° C. to about 80° C. Hydrofluorocarbons are commercial products available from a number of sources or may be prepared by methods known in the art. Representative hydrofluorocarbon compounds include but are not limited to fluoromethane (CH₃F, HFC-41), difluoromethane (CH₂F₂, HFC-32), trifluoromethane (CHF₃, HFC-23), pentafluoroethane (CF₃CHF₂, HFC-125), 1,1,2,2-tetrafluoroethane (CHF₂CHF₂, HFC-134), 1,1,1,2-tetrafluoroethane (CF₃CH₂F, HFC-134a), 1,1,1-trifluoroethane (CF₃CH₃, HFC-143a), 1,1-difluoroethane (CHF₂CH₃, HFC-152a), fluoroethane (CH₃CH₂F, HFC-161), 1,1,1,2,2,3,3-heptafluoropropane (CF₃CF₂CHF₂, HFC-227ca), 1,1,1,2,3,3,3-heptafluoropropane (CF₃CHFCF₃, HFC-227ea), 1,1,2,2,3,3-hexafluoropropane (CHF₂CF₂CHF₂, HFC-236ca), 1,1,1,2,2,3-hexafluoropropane (CF₃CF₃CH₂F, HFC-236cb), 1,1,1,2,3,3-hexafluoropropane (CF₃CHFCHF₂, HFC-236ea), 1,1,1,3,3,3-hexafluoropropane (CF₃CH₂CF₃, HFC-236fa), 1,1,2,2,3-pentafluoropropane (CHF₂CF₂CH₂F, HFC-245ca), 1,1,1,2,2-pentafluoropropane (CF₃CF₂CH₃, HFC-245cb), 1,1,2,3,3-pentafluoropropane (CHF₂CHFCHF₂, HFC-245ea), 1,1,1,2,3-pentafluoropropane (CF₃CHFCH₂F, HFC-245eb), 1,1,1,3,3-pentafluoropropane (CF₃CH₂CHF₂, HFC-245fa), 1,2,2,3-tetrafluoropropane (CH₂FCF₂CH₂F, HFC-254ca), 1,1,2,2-tetrafluoropropane (CHF₂CF₂CH₃, HFC-254cb), 1,1,2,3-tetrafluoropropane (CHF₂CHFCH₂F, HFC-254ea), 1,1,1,2-tetrafluoropropane (CF₃CHFCH₃, HFC-254eb), 1,1,3,3-tetrafluoropropane (CHF₂CH₂CHF₂, HFC-254fa), 1,1,1,3-tetrafluoropropane (CF₃CH₂CH₂F, HFC-254fb), 1,1,1-trifluoropropane (CF₃CH₂CH₃, HFC-263fb), 2,2-difluoropropane (CH₃CF₂CH₃, HFC-272ca), 1,2-difluoropropane (CH₂FCHFCH₃, HFC-272ea), 1,3-difluoropropane (CH₂FCH₂CH₂F, HFC-272fa), 1,1-difluoropropane (CHF₂CH₂CH₃, HFC-272fb), 2-fluoropropane (CH₃CHFCH₃, HFC-281ea), 1-fluoropropane (CH₂FCH₂CH₃, HFC-281fa), 1,1,2,2,3,3,4,4-octafluorobutane (CHF₂CF₂CF₂CHF₂, HFC-338pcc), 1,1,1,2,2,4,4,4-octafluorobutane (CF₃CH₂CF₂CF₃, HFC-338mf), 1,1,1,3,3-pentafluorobutane (CF₃CH₂CHF₂, HFC-365mfc), 1,1,1,2,3,4,4,5,5,5-decafluoropentane (CF₃CHFCHFCF₂CF₃, HFC-43-10mee), and 1,1,1,2,2,3,4,5,5,6,6,7,7,7-tetradecafluoroheptane (CF₃CF₂CHFCHFCF₂CF₂CF₃, HFC-63-14mee).

In some embodiments, working fluids may further comprise fluoroethers comprising at least one compound having carbon, fluorine, oxygen and optionally hydrogen, chlorine, bromine or iodine. Fluoroethers are commercially available or may be produced by methods known in the art. Representative fluoroethers include but are not limited to nonafluoromethoxybutane (C₄F₉OCH₃, any or all possible isomers or mixtures thereof); nonafluoroethoxybutane (C₄F₉OC₂H₅, any or all possible isomers or mixtures thereof); 2-difluoromethoxy-1,1,1,2-tetrafluoroethane (HFOC-236eaEβγ, or CHF₂OCHFCF₃); 1,1-difluoro-2-methoxyethane (HFOC-272fbEβγ, □CH₃OCH₂CHF₂); 1,1,1,3,3,3-hexafluoro-2-(fluoromethoxy)propane (HFOC-347mmzEβγ, or CH₂FOCH(CF₃)₂); 1,1,1,3,3,3-hexafluoro-2-methoxypropane (HFOC-356mmzEβγ, or CH₃OCH(CH₃)₂); 1,1,1,2,2-pentafluoro-3-methoxypropane (HFOC-365mcEγδ, or CF₃CF₂CH₂OCH₃); 2-ethoxy-1,1,1,2,3,3,3-heptafluoropropane (HFOC-467mmyEβγ, or CH₃CH₂OCF(CF₃)₂□; and mixtures thereof.

In some embodiments, working fluids may further comprise hydrocarbons comprising compounds having only carbon and hydrogen. Of particular utility are compounds having 3 to 7 carbon atoms. Hydrocarbons are commercially available through numerous chemical suppliers. Representative hydrocarbons include but are not limited to propane, n-butane, isobutane, cyclobutane, n-pentane, 2-methylbutane, 2,2-dimethylpropane, cyclopentane, n-hexane, 2-methylpentane, 2,2-dimethylbutane, 2,3-dimethylbutane, 3-methylpentane, cyclohexane, n-heptane, and cycloheptane.

In some embodiments, the working fluid may comprise hydrocarbons containing heteroatoms, such as dimethylether (DME, CH₃OCH₃). DME is commercially available.

In some embodiments, working fluids may further comprise carbon dioxide (CO₂), which is commercially available from various sources or may be prepared by methods known in the art.

In some embodiments, working fluids may further comprise ammonia (NH₃), which is commercially available from various sources or may be prepared by methods known in the art.

In some embodiments, the working fluid further comprises at least one compound selected from hydrofluorocarbons, fluoroethers, hydrocarbons, dimethyl ether (DME), carbon dioxide (CO₂), ammonia (NH₃), and iodotrifluoromethane (CF₃I).

In one embodiment, the working fluid comprises 1,2,3,3,3-pentafluoropropene (HFC-1225ye). In another embodiment, the working fluid further comprises difluoromethane (HFC-32). In yet another embodiment, the working fluid further comprises 1,1,1,2-tetrafluoroethane (HFC-134a).

In one embodiment, the working fluid comprises 2,3,3,3-tetrafluoropropene (HFC-1234yf). In another embodiment, the working fluid comprises HFC-1225ye and HFC-1234yf.

In one embodiment, the working fluid comprises 1,3,3,3-tetrafluoropropene (HFC-1234ze). In another embodiment, the working fluid comprises E-HFC-1234ze (or trans-HFC-1234ze).

In yet another embodiment, the working fluid further comprises at least one compound from the group consisting of HFC-134a, HFC-32, HFC-125, HFC-152a, and CF₃I.

In certain embodiments, working fluids may comprise a composition selected from the group consisting of:

HFC-32 and HFC-1225ye;

HFC-1234yf and CF₃I;

HFC-32, HFC-134a, and HFC-1225ye;

HFC-32, HFC-125, and HFC-1225ye;

HFC-32, HFC-1225ye, and HFC-1234yf;

HFC-125, HFC-1225ye, and HFC-1234yf;

HFC-32, HFC-1225ye, HFC-1234yf, and CF₃I;

HFC-134a, HFC-1225ye, and HFC-1234yf;

HFC-134a and HFC-1234yf;

HFC-32 and HFC-1234yf;

HFC-125 and HFC-1234yf;

HFC-32, HFC-125, and HFC-1234yf;

HFC-32, HFC-134a, and HFC-1234yf;

DME and HFC-1234yf;

HFC-152a and HFC-1234yf;

HFC-152a, HFC-134a, and HFC-1234yf;

HFC-152a, n-butane, and HFC-1234yf;

HFC-134a, propane, and HFC-1234yf;

HFC-125, HFC-152a, and HFC-1234yf;

HFC-125, HFC-134a, and HFC-1234yf;

HFC-32, HFC-1234ze, and HFC-1234yf;

HFC-125, HFC-1234ze, and HFC-1234yf;

HFC-32, HFC-1234ze, HFC-1234yf, and CF₃I;

HFC-134a, HFC-1234ze, and HFC-1234yf;

HFC-134a and HFC-1234ze;

HFC-32 and HFC-1234ze;

HFC-125 and HFC-1234ze;

HFC-32, HFC-125, and HFC-1234ze;

HFC-32, HFC-134a, and HFC-1234ze;

DME and HFC-1234ze;

HFC-152a and HFC-1234ze;

HFC-152a, HFC-134a, and HFC-1234ze;

HFC-152a, n-butane, and HFC-1234ze;

HFC-134a, propane, and HFC-1234ze;

HFC-125, HFC-152a, and HFC-1234ze; or

HFC-125, HFC-134a, and HFC-1234ze.

EXAMPLES Example 1 Performance Comparison

Automobile air conditioning systems with and without an intermediate heat exchanger are tested to determine if an improvement is seen with the IHX. The working fluid is a blend of 95% by weight HFC-1225ye and 5% by weight of HFC-32. Each system has a condenser, evaporator, compressor and a thermal expansion device. The ambient air temperature is 30° C. at the evaporator and the condenser inlets. Tests are performed for 2 compressor speeds, 1000 and 2000 rpm, and for 3 vehicle speeds: 25, 30, and 36 km/h. The volumetric flow rate of air on the evaporator is 380 m³/h.

The cooling capacity for the system with an IHX shows an increase of 4 to 7% as compared to the system with no IHX. The COP also shows an increase of 2.5 to 4% for the system with the IHX as compared to a system with no IHX.

Example 2 Improvement in Performance with Internal Heat Exchanger

Cooling performance is calculated for HFC-134a and HFC-1234yf both with and without an IHX. The conditions used are as follows:

Condenser temperature 55° C. Evaporator temperature  5° C. Superheat (absolute) 15° C. The data illustrating relative performance is shown in TABLE 5.

TABLE 5 Subcool, Capacity Compressor Test ° C. COP kJ/m³ work, kJ/kg HFC-134a, without 0 4.74 2250.86 29.6 IHX HFC-134a, with IHX 5.0 5.02 2381.34 29.6 HFC-134a, % 5.91 5.80 increase with IHX HFC-1234yf, without 0 4.64 2172.43 24.37 IHX HFC-1234yf with IHX 5.8 5.00 2335.38 24.37 HFC-1234yf, % 7.76 7.50 increase with IHX

The data above demonstrate an unexpected level of improvement in energy efficiency (COP) and cooling capacity for the fluoroolefin (HFC-1234yf) with the IHX, as compared to that gained by HFC-134a with the IHX. In particular, COP is increased by 7.67% and cooling capacity is increased by 7.50%.

It should be noted that the subcool difference arises from the differences in molecular weight, liquid density and liquid heat capacity for HFC-1234yf as compared to HFC-134a. Based on these parameters it is estimated that there would be a difference in subcool achieved with the different compounds. When the HFC-134a subcool is set to 5° C., the corresponding subcool for HFC-1234yf is calculated to be 5.8° C. 

What is claimed is:
 1. A method for exchanging heat in a vapor compression heat transfer system having a working fluid circulating therethrough, comprising the steps of: (a) circulating a working fluid comprising a fluoroolefin to an inlet of a first tube of an internal heat exchanger, through the internal heat exchanger and to an outlet thereof; (b circulating the working fluid from the outlet of the first tube of the internal heat exchanger to an inlet of an evaporator, through the evaporator to evaporate the working fluid and convert it into a gas, and through an outlet of the evaporator; (c) circulating the working fluid from the outlet of the evaporator to an inlet of a second tube of the internal heat exchanger to transfer heat from the liquid working fluid from the condenser to the gaseous working fluid from the evaporator, through the internal heat exchanger, and to an outlet of the second tube; (d) circulating the working fluid from the outlet of the second tube of the internal heat exchanger to an inlet of a compressor, through the compressor to compress the working fluid gas, and to an outlet of the compressor; (e) circulating the working fluid from the outlet of the compressor to an inlet of a condenser and through the condenser to condense the compressed working fluid gas into a liquid, and to an outlet of the condenser; (f) circulating the working fluid from the outlet of the condenser to an inlet of the first tube of the intermediate heat exchanger to transfer heat from the liquid from the condenser to the gas from the evaporator, and to an outlet of the second tube; and (g) circulating the working fluid from the outlet of the second tube of the internal heat exchanger back to the evaporator.
 2. The method of claim 1, where the fluoroolefin is at least one compound selected from the group consisting of: (i) fluoroolefins of the formula E- or Z—R¹CH═CHR², wherein R¹ and R² are, independently, C₁ to C₆ perfluoroalkyl groups; (ii) cyclic fluoroolefins of the formula cyclo-[CX═CY(CZW)_(n)—], wherein X, Y, Z, and W, independently, are H or F, and n is an integer from 2 to 5; and (iii) fluoroolefins selected from the group consisting of: 1,2,3,3,3-pentafluoro-1-propene (CHF═CFCF₃), 1,1,3,3,3-pentafluoro-1-propene (CF₂═CHCF₃), 1,1,2,3,3-pentafluoro-1-propene (CF₂═CFCHF₂), 1,2,3,3-tetrafluoro-1-propene (CHF═CFCHF₂), 2,3,3,3-tetrafluoro-1-propene (CH₂═CFCF₃), 1,3,3,3-tetrafluoro-1-propeneCHF=CHCF₃), 1,1,2,3-tetrafluoro-1-propene (CF₂═CFCH₂F), 1,1,3,3-tetrafluoro-1-propene (CF₂═CHCHF₂), 1,2,3,3-tetrafluoro-1-propene (CHF═CFCHF₂), 3,3,3-trifluoro-1-propene (CH₂═CHCF₃), 2,3,3-trifluoro-1-propene (CHF₂CF═CH₂); 1,1,2-trifluoro-1-propene (CH₃CF═CF₂); 1,2,3-trifluoro-1-propene (CH₂FCF═CF₂); 1,1,3-trifluoro-1-propene (CH₂FCH═CF₂); 1,3,3-trifluoro-1-propene (CHF₂CH═CHF); 1,1,1,2,3,4,4,4-octafluoro-2-butene (CF₃CF═CFCF₃); 1,1,2,3,3,4,4,4-octafluoro-1-butene (CF₃CF₂CF═CF₂); 1,1,1,2,4,4,4-heptafluoro-2-butene (CF₃CF═CHCF₃); 1,2,3,3,4,4,4-heptafluoro-1-butene (CHF═CFCF₂CF₃); 1,1,1,2,3,4,4-heptafluoro-2-butene (CHF₂CF═CFCF₃); 1,3,3,3-tetrafluoro-2-(trifluoromethyl)-1-propene ((CF₃)₂C═CHF); 1,1,3,3,4,4,4-heptafluoro-1-butene (CF₂═CHCF₂CF₃); 1,1,2,3,4,4,4-heptafluoro-1-butene (CF₂═CFCHFCF₃); 1,1,2,3,3,4,4-heptafluoro-1-butene (CF₂═CFCF₂CHF₂); 2,3,3,4,4,4-hexafluoro-1-butene (CF₃CF₂CF═CH₂); 1,3,3,4,4,4-hexafluoro-1-butene (CHF═CHCF₂CF₃); 1,2,3,4,4,4-hexafluoro-1-butene (CHF═CFCHFCF₃); 1,2,3,3,4,4-hexafluoro-1-butene (CHF═CFCF₂CHF₂); 1,1,2,3,4,4-hexafluoro-2-butene (CHF₂CF═CFCHF₂); 1,1,1,2,3,4-hexafluoro-2-butene (CH₂FCF═CFCF₃); 1,1,1,2,4,4-hexafluoro-2-butene (CHF₂CH═CFCF₃); 1,1,1,3,4,4-hexafluoro-2-butene (CF₃CH═CFCHF₂); 1,1,2,3,3,4-hexafluoro-1-butene (CF₂═CFCF₂CH₂F); 1,1,2,3,4,4-hexafluoro-1-butene (CF₂═CFCHFCHF₂); 3,3,3-trifluoro-2-(trifluoromethyl)-1-propene (CH₂═C(CF₃)₂); 1,1,1,2,4-pentafluoro-2-butene (CH₂FCH═CFCF₃); 1,1,1,3,4-pentafluoro-2-butene (CF₃CH═CFCH₂F); 3,3,4,4,4-pentafluoro-1-butene (CF₃CF₂CH═CH₂); 1,1,1,4,4-pentafluoro-2-butene (CHF₂CH═CHCF₃); 1,1,1,2,3-pentafluoro-2-butene (CH₃CF═CFCF₃); 2,3,3,4,4-pentafluoro-1-butene (CH₂═CFCF₂CHF₂); 1,1,2,4,4-pentafluoro-2-butene (CHF₂CF═CHCHF₂); 1,1,2,3,3-pentafluoro-1-butene (CH₃CF₂CF═CF₂); 1,1,2,3,4-pentafluoro-2-butene (CH₂FCF═CFCHF₂); 1,1,3,3,3-pentafluoro-2-methyl-1-propene (CF₂═C(CF₃)(CH₃)); 2-(difluoromethyl)-3,3,3-trifluoro-1-propene (CH₂═C(CHF₂)(CF₃)); 2,3,4,4,4-pentafluoro-1-butene (CH₂═CFCHFCF₃); 1,2,4,4,4-pentafluoro-1-butene (CHF═CFCH₂CF₃); 1,3,4,4,4-pentafluoro-1-butene (CHF═CHCHFCF₃); 1,3,3,4,4-pentafluoro-1-butene (CHF═CHCF₂CHF₂); 1,2,3,4,4-pentafluoro-1-butene (CHF═CFCHFCHF₂); 3,3,4,4-tetrafluoro-1-butene (CH₂═CHCF₂CHF₂); 1,1-difluoro-2-(difluoromethyl)-1-propene (CF₂═C(CHF₂)(CH₃)); 1,3,3,3-tetrafluoro-2-methyl-1-propene (CHF═C(CF₃)(CH₃)); 3,3-difluoro-2-(difluoromethyl)-1-propene (CH₂═C(CHF₂)₂); 1,1,1,2-tetrafluoro-2-butene (CF₃CF═CHCH₃); 1,1,1,3-tetrafluoro-2-butene (CH₃CF═CHCF₃); 1,1,1,2,3,4,4,5,5,5-decafluoro-2-pentene (CF₃CF═CFCF₂CF₃); 1,1,2,3,3,4,4,5,5,5-decafluoro-1-pentene (CF₂═CFCF₂CF₂CF₃); 1,1,1,4,4,4-hexafluoro-2-(trifluoromethyl)-2-butene ((CF₃)₂C═CHCF₃); 1,1,1,2,4,4,5,5,5-nonafluoro-2-pentene (CF₃CF═CHCF₂CF₃); 1,1,1,3,4,4,5,5,5-nonafluoro-2-pentene (CF₃CH═CFCF₂CF₃); 1,2,3,3,4,4,5,5,5-nonafluoro-1-pentene (CHF═CFCF₂CF₂CF₃); 1,1,3,3,4,4,5,5,5-nonafluoro-1-pentene (CF₂═CHCF₂CF₂CF₃); 1,1,2,3,3,4,4,5,5-nonafluoro-1-pentene (CF₂═CFCF₂CF₂CHF₂); 1,1,2,3,4,4,5,5,5-nonafluoro-2-pentene (CHF₂CF═CFCF₂CF₃); 1,1,1,2,3,4,4,5,5-nonafluoro-2-pentene (CF₃CF═CFCF₂CHF₂); 1,1,1,2,3,4,5,5,5-nonafluoro-2-pentene (CF₃CF═CFCHFCF₃); 1,2,3,4,4,4-hexafluoro-3-(trifluoromethyl)-1-butene (CHF═CFCF(CF₃)₂); 1,1,2,4,4,4-hexafluoro-3-(trifluoromethyl)-1-butene (CF₂═CFCH(CF₃)₂); 1,1,1,4,4,4-hexafluoro-2-(trifluoromethyl)-2-butene (CF₃CH═C(CF₃)₂); 1,1,3,4,4,4-hexafluoro-3-(trifluoromethyl)-1-butene (CF₂═CHCF(CF₃)₂); 2,3,3,4,4,5,5,5-octafluoro-1-pentene (CH₂═CFCF₂CF₂CF₃); 1,2,3,3,4,4,5,5-octafluoro-1-pentene (CHF═CFCF₂CF₂CHF₂); 3,3,4,4,4-pentafluoro-2-(trifluoromethyl)-1-butene (CH₂═C(CF₃)CF₂CF₃); 1,1,4,4,4-pentafluoro-3-(trifluoromethyl)-1-butene (CF₂═CHCH(CF₃)₂); 1,3,4,4,4-pentafluoro-3-(trifluoromethyl)-1-butene (CHF═CHCF(CF₃)₂); 1,1,4,4,4-pentafluoro-2-(trifluoromethyl)-1-butene (CF₂═C(CF₃)CH₂CF₃); 3,4,4,4-tetrafluoro-3-(trifluoromethyl)-1-butene ((CF₃)₂CFCH═CH₂); 3,3,4,4,5,5,5-heptafluoro-1-pentene (CF₃CF₂CF₂CH═CH₂); 2,3,3,4,4,5,5-heptafluoro-1-pentene (CH₂═CFCF₂CF₂CHF₂); 1,1,3,3,5,5,5-heptafluoro-1-butene (CF₂═CHCF₂CH₂CF₃); 1,1,1,2,4,4,4-heptafluoro-3-methyl-2-butene (CF₃CF═C(CF₃)(CH₃)); 2,4,4,4-tetrafluoro-3-(trifluoromethyl)-1-butene (CH₂═CFCH(CF₃)₂); 1,4,4,4-tetrafluoro-3-(trifluoromethyl)-1-butene (CHF═CHCH(CF₃)₂); 1,1,1,4-tetrafluoro-2-(trifluoromethyl)-2-butene (CH₂FCH═C(CF₃)₂); 1,1,1,3-tetrafluoro-2-(trifluoromethyl)-2-butene (CH₃CF═C(CF₃)₂); 1,1,1-trifluoro-2-(trifluoromethyl)-2-butene ((CF₃)₂C═CHCH₃); 3,4,4,5,5,5-hexafluoro-2-pentene (CF₃CF₂CF═CHCH₃); 1,1,1,4,4,4-hexafluoro-2-methyl-2-butene (CF₃C(CH₃)═CHCF₃); 3,3,4,5,5,5-hexafluoro-1-pentene (CH₂═CHCF₂CHFCF₃); 4,4,4-trifluoro-2-(trifluoromethyl)-1-butene (CH₂═C(CF₃)CH₂CF₃); 1,1,2,3,3,4,4,5,5,6,6,6-dodecafluoro-1-hexene (CF₃(CF₂)₃CF═CF₂); 1,1,1,2,2,3,4,5,5,6,6,6-dodecafluoro-3-hexene (CF₃CF₂CF═CFCF₂CF₃); 1,1,1,4,4,4-hexafluoro-2,3-bis(trifluoromethyl)-2-butene ((CF₃)₂C═C(CF₃)₂); 1,1,1,2,3,4,5,5,5-nonafluoro-4-(trifluoromethyl)-2-pentene ((CF₃)₂CFCF═CFCF₃); 1,1,1,4,4,5,5,5-octafluoro-2-(trifluoromethyl)-2-pentene ((CF₃)₂C═CHC₂F₅); 1,1,1,3,4,5,5,5-octafluoro-4-(trifluoromethyl)-2-pentene ((CF₃)₂CFCF═CHCF₃); 3,3,4,4,5,5,6,6,6-nonafluoro-1-hexene (CF₃CF₂CF₂CF₂CH═CH₂); 4,4,4-trifluoro-3,3-bis(trifluoromethyl)-1-butene (CH₂═CHC(CF₃)₃); 1,1,1,4,4,4-hexafluoro-3-methyl-2-(trifluoromethyl)-2-butene ((CF₃)₂C═C(CH₃)(CF₃)); 2,3,3,5,5,5-hexafluoro-4-(trifluoromethyl)-1-pentene (CH₂═CFCF₂CH(CF₃)₂); 1,1,1,2,4,4,5,5,5-nonafluoro-3-methyl-2-pentene (CF₃CF═C(CH₃)CF₂CF₃); 1,1,1,5,5,5-hexafluoro-4-(trifluoromethyl)-2-pentene (CF₃CH═CHCH(CF₃)₂); 3,4,4,5,5,6,6,6-octafluoro-2-hexene (CF₃CF₂CF₂CF═CHCH₃); 3,3,4,4,5,5,6,6-octafluoro1-hexene (CH₂═CHCF₂CF₂CF₂CHF₂); 1,1,1,4,4-pentafluoro-2-(trifluoromethyl)-2-pentene ((CF₃)₂C═CHCF₂CH₃); 4,4,5,5,5-pentafluoro-2-(trifluoromethyl)-1-pentene (CH₂═C(CF₃)CH₂C₂F₅); 3,3,4,4,5,5,5-heptafluoro-2-methyl-1-pentene (CF₃CF₂CF₂C(CH₃)═CH₂); 4,4,5,5,6,6,6-heptafluoro-2-hexene (CF₃CF₂CF₂CH═CHCH₃); 4,4,5,5,6,6,6-heptafluoro-1-hexene (CH₂═CHCH₂CF₂C₂F₅); 1,1,1,2,2,3,4-heptafluoro-3-hexene (CF₃CF₂CF═CFC₂H₅); 4,5,5,5-tetrafluoro-4-(trifluoromethyl)-1-pentene (CH₂═CHCH₂CF(CF₃)₂); 1,1,1,2,5,5,5-heptafluoro-4-methyl-2-pentene (CF₃CF═CHCH(CF₃)(CH₃)); 1,1,1,3-tetrafluoro-2-(trifluoromethyl)-2-pentene ((CF₃)₂C═CFC₂H₅); 1,1,1,2,3,4,4,5,5,6,6,7,7,7-tetradecafluoro-2-heptene (CF₃CF═CFCF₂CF₂C₂F₅); 1,1,1,2,2,3,4,5,5,6,6,7,7,7-tetradecafluoro-3-heptene (CF₃CF₂CF═CFCF₂₂F₅); 1,1,1,3,4,4,5,5,6,6,7,7,7-tridecafluoro-2-heptene (CF₃CH═CFCF₂CF₂C₂F₅); 1,1,1,2,4,4,5,5,6,6,7,7,7-tridecafluoro-2-heptene (CF₃CF═CHCF₂CF₂C₂F₅); 1,1,1,2,2,4,5,5,6,6,7,7,7-tridecafluoro-3-heptene (CF₃CF₂CH═CFCF₂C₂F₅); 1,1,1,2,2,3,5,5,6,6,7,7,7-tridecafluoro-3-heptene (CF₃CF₂CF═CHCF₂C₂F₅); pentafluoroethyl trifluorovinyl ether (CF₂═CFOCF₂CF₃); and trifluoromethyl trifluorovinyl ether (CF₂═CFOCF₃).
 3. The method of claim 1, where the working fluid in the second tube flows in a countercurrent direction to the direction of flow of the working fluid in the first tube, thereby cooling the working fluid in the first tube and heating the working fluid in the second tube.
 4. The method of claim 1, where the first tube has a larger diameter than the second tube, and the second tube is disposed concentrically in the first tube, and a hot liquid in the first tube surrounds a cool gas in the second tube.
 5. The method of claim 1, wherein the condensing step comprises: (i) circulating the working fluid to a back row of a dual-row condenser, where the back row receives the working fluid at a first temperature; and (ii) circulating the working fluid to a front row of the dual-row condenser, where the front row receives the working fluid at a second temperature, where the second temperature is less than the first temperature, so that air which travels across the front row and the back row is preheated, whereby the temperature of the air is greater when it reaches the back row than when it reaches the front row.
 6. The method of claim 1, wherein the evaporating step comprises: (i) passing the working fluid through an inlet of a dual-row evaporator having a first row and a second row, (ii) circulating the working fluid in the first row in a direction perpendicular to the flow of fluid through the inlet of the evaporator, and (iii) circulating the working fluid in the second row in a direction generally counter to the direction of the flow of the working fluid through the inlet.
 7. The method of claim 1, wherein the working fluid further comprises at least one compound selected from hydrofluorocarbons, fluoroethers, hydrocarbons, dimethyl ether (DME), carbon dioxide (CO₂), ammonia (NH₃), and iodotrifluoromethane (CF₃I).
 8. The method of claim 5, wherein the working fluid further comprises at least one compound selected from hydrofluorocarbons, fluoroethers, hydrocarbons, dimethyl ether (DME), carbon dioxide (CO₂), ammonia (NH₃), and iodotrifluoromethane (CF₃I).
 9. The method of claim 6, wherein the working fluid further comprises at least one compound selected from hydrofluorocarbons, fluoroethers, hydrocarbons, dimethyl ether (DME), carbon dioxide (C002), ammonia (NH₃), and iodotrifluoromethane (CF₃I).
 10. The method of claim 1, wherein the fluoroolefin comprises HFC-1234yf.
 11. The method of claim 5, wherein the fluoroolefin comprises HFC-1234yf.
 12. The method of claim 6, wherein the fluoroolefin comprises HFC-1234yf.
 13. The method of claim 10, wherein the coefficient of performance and the cooling capacity of the system is increased by at least 7.5% as compared to a system which uses HFC-134a as the working fluid.
 14. The method of claim 11, wherein the coefficient of performance and the cooling capacity of the system is increased by at least 7.5% as compared to a system which uses HFC-134a as the working fluid.
 15. The method of claim 12, wherein the coefficient of performance and the cooling capacity of the system is increased by at least 7.5% as compared to a system which uses HFC-134a as the working fluid.
 16. A vapor compression heat transfer system for exchanging heat, comprising: (a) an evaporator having an inlet and an outlet; (b) a compressor having an inlet and an outlet, wherein the inlet is connected to the outlet of the evaporator; (c) a dual-row condenser connected to the outlet of the compressor, the dual-row condenser having: (i) an inlet, (ii) a first row connected to the inlet, the first row comprising a first inlet manifold and a plurality of channels for allowing a working fluid at a first temperature to flow into the manifold and then through the channels in at least one direction and collect in a second outlet manifold, (iii) a second row connected to the first row, the second row comprising a plurality of channels for conducting a working fluid at a second temperature less than the refrigerant in the first row, (iv) conduit connecting the first row to the second row; and (d) an intermediate heat exchanger, having: (i) a first tube having an inlet connected to an exit of the condenser and an outlet, and (ii) a second tube having an inlet connected to an outlet and an outlet connected to an inlet of the dual-row condenser; and wherein the inlet of the evaporator is connected to the outlet of the first tube of the intermediate heat exchanger.
 17. A vapor compression heat transfer system for exchanging heat, comprising: (a) a dual-row evaporator for evaporating a working fluid, the evaporator having an inlet and an outlet; (b) a compressor having an inlet and an outlet, wherein the inlet is connected to the outlet of the evaporator; (c) a condenser having an inlet and an outlet, wherein the inlet is connected to the outlet of the compressor; and (d) an intermediate heat exchanger having: (i) a first tube having an inlet connected to an exit line of a condenser and an outlet connected to an inlet line of the evaporator; (ii) a second tube having an inlet connected to an outlet line of the evaporator having an outlet. 